Manual transmissions first gear ratios

[bax]

I was asked a question that I did not have a good answer for. The guy has a bronco with an ax15 in it. Says he hates first gear. Its too low . I told him the AX15 docent have a real deep first gear. I also added that it has the highest first gear in any trans that will adapt a transfer case to the back of.. Problem is I may be lying because I am not up to speed on any of the" newer "transmissions that may be available now. Any information, Am I wrong, again? He is looking for more of a car / mustang type manual trans gearing.

 

[ntsqd]

4:1 is about as low as any of those Aisin R series transmissions go. I'd expect that the trans used in the Supras would have the tallest first gear and may even be a close ratio box. I just don't know enough to know if it is possible to stuff those gears in AX15's case and still be able to use the AX15's output shaft.

 

[DirtDonk]

Do you know what differential gear ratio your friend is running? Tire size?
That might be why a high-three, or low-four first gear feels too low for his tastes.
Hah! I remember when that was not a thing. Not possible to have too low of a first gear!
Bring on the NP435s!

Paul

 

[ntsqd]

Bring on the SM420's!!

Then there's that Allison MDT auto with an 8:1 first gear (but no OD and no lock-up) that are, apparently, commonly found in trash trucks. Like with NP's & SM's it normally starts out in 2nd and you have to manually select 1st.

 

[DirtDonk]

Young whippersnappers probably never heard the phrase "granny gear" or "compound low" or one or two others that I can't think of at the moment.
Just speaking a foreign language.

Paul

 

[Broncobowsher]

Just for data...
My brother just got a new Rubicon with the 6-speed and standard 4.10 gears (factory options as low as 4.88 are available)
Bone stock and he thinks 1st is too low. Also thinks 6th is too high.
My daily driver Xterra has a 4.3 1st and .75 OD on a 3.69 final drive. First is a dead stop gear, but with any roll it gets skipped. It is nice in bumper to bumper traffic. And 6th is perfect.
Back when I ran the NP435 and 4.11s I would use use the granny in parking lots and bumper to bumper traffic.

 

[bfoldy]

No, I don’t think you’re lying. It seems the AX 15 is about as car like as you can get for a manual transmission that will go into a bronco and adapt to a transfer case. The first gear ratio is 3.83.

(Corrected earlier typo after 904Bronco posted)
NV3550 (4.01)
ZF S5-42 (5.72)
NV4500 (5.61)
TR4050 (6.16)
T18/T19 (6.32)
NP435 (6.69)


Sent from my iPhone using Tapatalk

 

[904Bronco]

The Tremec TR4050 has a 6.16 granny gear, OD is 0.76. Great replacement for the factory NP435 in my Gen II Bronco with 4:11's.

 

[MarsChariot]

NV3550 1st is 4.01. Try combining that with a 4.11 rear. I frequently start in second. But I can dig out if I want too.

 

[Broncobowsher]

M5R2? (truck version). I know there were a couple different sets of gears used in the super coupe but I have yet to hear if they can be swapped into a truck case.

 

[bax]

No, I don’t think you’re lying. It seems the AX 15 is about as car like as you can get for a manual transmission that will go into a bronco and adapt to a transfer case. The first gear ratio is 3.83.

NV3550 (4.01), TR4050 (4.16), ZF S5-42 (5.72), NV4500 (5.61), T18/T19 (6.32), and NP435 (6.69).


Sent from my iPhone using Tapatalk

Good not to be a lying.

 

[73azbronco]

Young whippersnappers probably never heard the phrase "granny gear" or "compound low" or one or two others that I can't think of at the moment.
Just speaking a foreign language.

Paul

bingo, it's designed to be hated, unless you are stopped going up a 45 degree incline, then you can crawl right up.

 

[TAC71]

M5R2? (truck version). I know there were a couple different sets of gears used in the super coupe but I have yet to hear if they can be swapped into a truck case.

I put a 91 Super Coupe m5r2 trans into one of my broncos. 3.75 first if remember right, I think there 2 different 1st gear ratios. Put a 4wd version tailhousing on it and then machined up an adapter to go to a D20. The trans already has 28 spline output and bolts up to a smallblock.

 

[Broncobowsher]

I remember there being 2 different super coupe ratios, year dependent.
And those are different than the truck ratios.

Very cool that someone did the car ratios with 4WD. Had not thought of just swapping the tail housing. Did you keep teh super coupe shifter, or early truck shifter, or late truck (rear position) shifter?

 

[.94 OR]

Any chance the M5r1 (Ranger gearbox) can donate the top shifter cover to the M5r2 box since the shifter position is also in the rear and the shift tower appears shorter?

 

[ntsqd]

With more car-like gear ratios being desired the taller shifter tower will result in a shorter shifter throw. Which is also more car-like. May be desirable in this case.

 

[.94 OR]

So a Ranger would have more of a "truck" feel than an F150 with their respective M5 version gearboxes due to the shifter tower height?

 

[ntsqd]

That would depend on the lever length and the resulting shift lever ratio.

 

[TAC71]

I did the M5R2 swap 14 years ago , I think I used the SC shift tower. The stick is long to get it up to bronco height. Not an overly long throw, but it is more trucklike. Drives beautiful though.

 

[.94 OR]

I did the M5R2 swap 14 years ago , I think I used the SC shift tower. The stick is long to get it up to bronco height. Not an overly long throw, but it is more trucklike. Drives beautiful though.

What did you use for an adapter to the D20?